B737-700 first officer reports being cleared to las via bce and the GRNPA1 arrival. Due to weather d...

Narrative:

Due to GPS jamming in ZLC airspace and to the fact the airport was using a north flow instead of the south flow; dispatch had planned and filed us for; and we received a pre-departure clearance that was amended to use a non-RNAV departure that worked with a north flow. Our clearance read: ... Bce GRNPA1 klas.after departure; we needed to deviate around some thunderstorms in the area; and center cleared us to do so direct mlf when able. After checking in with los angeles center; we were told; 'cleared direct milford; grnpa 1 arrival.' since our pre departure clearance included the grnpa 1 already and it was already programmed into the FMC; we didn't realize mlf had its own transition on the GRNPA1. After passing mlf and proceeding toward bce; center asked if we were on the arrival. That's when we first realized the clearance had been different from what we had programmed and made the turn to ksino to re-join the arrival. There were no observed traffic conflicts due to our deviation.I should have referenced the STAR and queried ATC to clarify the clearance. Also had ATC used the phrase 'cleared direct milford; grnpa 1; milford transition' it would have alerted us to that the fact that the transition we were cleared to use had been changed.

Original NASA ASRS Text

Title: B737-700 First Officer reports being cleared to LAS via BCE and the GRNPA1 arrival. Due to weather deviations the route is changed to direct to MLF and the GRNPA1. The crew does not notice that MLF is a transition on the GRNPA1 and turns to BCE after MLF. ATC intervenes.

Narrative: Due to GPS jamming in ZLC airspace and to the fact the airport was using a north flow instead of the south flow; Dispatch had planned and filed us for; and we received a pre-departure clearance that was amended to use a non-RNAV departure that worked with a north flow. Our clearance read: ... BCE GRNPA1 KLAS.After departure; we needed to deviate around some thunderstorms in the area; and Center cleared us to do so direct MLF when able. After checking in with Los Angeles Center; we were told; 'Cleared direct Milford; GRNPA 1 Arrival.' Since our PDC included the GRNPA 1 already and it was already programmed into the FMC; we didn't realize MLF had its own transition on the GRNPA1. After passing MLF and proceeding toward BCE; Center asked if we were on the arrival. That's when we first realized the clearance had been different from what we had programmed and made the turn to KSINO to re-join the arrival. There were no observed traffic conflicts due to our deviation.I should have referenced the STAR and queried ATC to clarify the clearance. Also had ATC used the phrase 'cleared direct MILFORD; GRNPA 1; MILFORD transition' it would have alerted us to that the fact that the transition we were cleared to use had been changed.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1259699
Time
Date	201505
Local Time Of Day	0601-1200
Place
Locale Reference	LAS.Airport
State Reference	NV
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	STAR GRNPA ONE
Flight Plan	IFR
Component
Aircraft Component	FMS/FMC
Person 1
Function	First Officer
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 142
Events
Anomaly	Deviation - Procedural Published Material / Policy Deviation - Procedural Clearance Deviation - Track / Heading All Types Inflight Event / Encounter Weather / Turbulence

B737-700 first officer reports being cleared to las via bce and the GRNPA1 arrival. Due to weather deviations the route is changed to direct to mlf and the GRNPA1. The crew does not notice that mlf is a transition on the GRNPA1 and turns to bce after mlf. ATC intervenes.